HVAC systems for motor vehicles generally include molded plastic case sections that are joined together by various means. If the joint between the sections of the case does not have an air-tight seal, then it is possible for air to leak from the case which may result in loss of comfort in the passenger compartment of the motor vehicle, undesirable noise, or both.
There are several methods to provide sealing at the joints of the case. One method is to use a tongue and groove joint as shown in U.S. Pat. No. 5,699,601 to Gilliam et al. To maintain moldability and assemble-ability of the case sections, the tolerances of the tongue and groove are such that only at maximum material condition does the tongue have line-on-line contact within the groove. At all other conditions, there is a gap between the tongue and the groove. Other methods relate to putting a sealing material such as foam, sealant, or seals between sections of the case to seal any irregularities. The addition of foam, sealant, or seals may add cost and can misassembled.
U.S. Pat. No. 7,036,825 to Pettitt et al. teaches a case with a tongue and groove arrangement where the tongue is wider than the groove. The tongue has a slot which splits the tongue into first and second forks that compress together as the tongue is inserted into the groove in order to ensure that the tongue seals against the groove over the entire tolerance range of the tongue and groove. While this arrangement may be effective, the split tongue adds size to the joint which may be undesirable when the space available for the case within the motor vehicle is limited.
What is needed is case for a HVAC system minimizes or eliminates one or more of the shortcomings as set forth above.